SPIDER is the full-scale prototype of the plasma source of the negative-ion driven neutral beam injector for the heating and current drive of the ITER plasma. The uniqueness and complexity of the system requested this ad hoc test stand aiming at optimizing the performance of the RF inductively generated plasma, negative ion production and extraction, electron filtering, and robustness and controllability of all systems required to work together. After about three years of operation, presently SPIDER is in a long shutdown, in which the whole plasma source and accelerator were dismounted. In this phase, additional modifications with respect to the original design will be introduced to improve the system performance, driven by the experience acquired in the last years. These include the addition of further sets of permanent magnets in the plasma source expansion chamber and around the RF drivers, with the aim of improving the plasma confinement and consequently its density and possibly its uniformity. The present paper reports the study and the analyses behind this modification, which impacts on the original already complex magnetic configuration, made particularly difficult by the limited space available and the high voltages. The use of ferromagnetic shields, necessary to limit stray fields possibly increasing the breakdown probability, make the design particularly complex because of the greater impact on the previous configuration. An iterative process between analyses to determine the ideal configuration and CAD verifications was required. The analyses had to take into account the new magnetic configuration to be created in the particular area of interest, and the overall configuration in order to not compromise its efficacy.

In ITER and next step fusion reactors, the chosen materials for the first wall are Beryllium and Tungsten because of their good thermodynamic and mechanical properties, low level of erosion, neutron activation, and Tritium retention. However, radiation events due to the release of such high Z materials, can be responsible of plasma cooling, which can affect the ELM dynamics [A.R. Field et al. 2021 Plasma Phys. Control. Fusion 63 095,013], trigger MHD instabilities [G. Pucella et al. 2021 Nucl. Fusion 61 046,020], and inhibit the achievement of thermonuclear temperatures. For these reasons, over the years, methods to control the radiation level have been developed and integrated in the scenario design development. JET is the ideal testbed experiment to conduct radiation control studies being equipped with an ITER-like wall and able to operate with Tritium and Deuterium-Tritium fuel mixtures in plasmas with input power up to 33 MW. In this work, radiation control in JET ITER-like wall baseline plasmas during Tritium and Deuterium-Tritium baseline operations is reported, complimenting the work presented in [L. Piron et al. Radiation Control in Deuterium, Tritium and Deuterium-Tritium JET baseline plasmas - part I]. The behavior of radiation control methods has been investigated statistically. Such analysis suggests that, in Tritium hollow density profiles develop because of the high density level achieved at the plasma edge. This turns out to affect the ELM dynamics, exacerbating the radiation control. A possible solution to counter radiation build up is proposed and consists in exploiting the presence of error field correction coils to mitigate the ELM dynamics, and to induce density pump-out, thus affecting the density profile evolution.

The achievement of a steady ELMy H-mode phase with high ion temperature, but without a gradual rise in plasma radiation, has been a crucial point to establish high plasma performance scenarios in JET ITER-like-wall plasmas. Indeed, radiation events, due to the release of high Z impurities, such as Nickel and Copper, and W sputtered from the divertor, can strongly reduce the power crossing the plasma separatrix and slow the ELMs dynamics, thus inducing H to L transition. In particular, in JET baseline plasmas, because of the outward neoclassical transport [A.R. Field et al 2021 Plasma Phys. Control. Fusion 63 095013], plasma impurities are mainly localized in the mantle region, as detected by a real-time surrogate model for bolometer tomography based on machine learning [D.R. Ferreira et al 2021 Fusion Engineering and Design 164], and the consequent excessive radiation in this region is the main cause of plasma termination in recent Deuterium, Tritium and Deuterium-Tritium operations. To guarantee impurity accumulation being flushed by the ELMs, ELM control schemes, which ensure a throughput of particles, either via gas fueling and via pellets, have been exploited. In this work, the staged approach strategy towards radiation control, which allowed to sustain for more than 10 s Tritium and Deuterium-Tritium baseline discharges without radiation issues, is presented.

Operation of a magnetic fusion experiment, such as JET, relies on the availability of real-time (RT) control schemes, which supervise the plasma as it approaches the expected target performance while maintaining the integrity of the machine and its subsystems. At JET, there have been a series of recent efforts since (Lennholm M. et al 2017 Fusion Engineering and Design 123 535-540) to develop and test RT control schemes in preparation for the upcoming Deuterium-Tritium (DT) campaign. When operating JET in DT, each plasma discharge will in fact be a precious resource, being both T and neutron budget limited. Among the developed control schemes, this paper deals with the isotope ratio controller, which will maintain the required 50:50 DT ratio needed to favor nuclear fusion processes; the dud detector (L. Piron et al 2019 Fusion Engineering and Design 146 1364-1368), which will terminate a discharge moving toward controllers for detecting excessive radiation. Moreover, brand-new detectors, also based on machine learning approaches, have been implemented for detecting off-normal events or pre-disruptive states and have been included in the Plasma Event TRiggering and Alarms system (C.I. Stuart et al 2020 SOFT conference). Work is also ongoing to deploy into JET the RAPTOR suite, a RT observer for plasma state monitoring (C. Piron et al 2020 SOFT conference), and to identify control schemes within RAPTOR capabilities, which could contribute to support the development of high performance plasma scenarios.

The modelling of JET corner configurations, in which the strike points are positioned deep in the corners of the divertor, is extremely challenging for edge plasma fluid modelling tools. To circumvent this technical limitation, a geometrical approximation has been proposed, consisting in considering an artificial minor modification of the geometry of the divertor targets plates. In this paper, we investigate how significantly this approximation impacts the output of transport simulations. Using the SOLEDGE2D-EIRENE transport code which has the unique capability to be able to cope with both the full and the approximated geometry, we have performed a density scan in H-mode for pulses in which the outer strike-point lies in the corner of the divertor. We report here how simulations in the artificial geometry differ from the ones in unaltered geometry. At the exception of low density cases, mid-plane profiles in the closed field lines region and the near scrape-off layer are little impacted. Further out however, in flux-surfaces that are concerned by the geometrical modification, we find that modifying the geometry leads to a strong overestimate of the plasma density. The density perturbation is not local and concerns the whole flux surfaces. Although the divertor geometry is modified only on the outer side, the largest impact is found at the inner divertor where densities are systematically overestimated by a factor that can exceed 10 in low density cases in the far Scrape-Off Layer (SOL) and temperature underestimated by 10 to 20 eV in most of the studied density range. The near SOL and strike point peak values are also impacted in the same direction with density changes by a factor of 2. As a consequence, the threshold to detachment of the inner divertor is found lower in the approximate geometry than in the unaltered one. Due to the large flux expansion between the outer and the inner target, the difference in plasma is especially sensitive at the top of the inner divertor baffle, which could have consequence on the evaluation of physical sputtering at that critical location.

In the "precision oncology" era the characterization of tumor genetic features is a pivotal step in cancer patients' management. Liquid biopsy approaches, such as analysis of cell-free DNA from plasma, represent a powerful and noninvasive strategy to obtain information about the genomic status of the tumor. Sequencing-based analyses of cell-free DNA, currently performed with second generation sequencers, are extremely powerful but poorly scalable and not always accessible also due to instrumentation costs. Third generation sequencing platforms, such as Nanopore sequencers, aim at overcoming these obstacles but, unfortunately, are not designed for cell-free DNA analysis. Here we present a customized workflow to exploit low-coverage Nanopore sequencing for the detection of copy number variations from plasma of cancer patients. Whole genome molecular karyotypes of 6 lung cancer patients and 4 healthy subjects were successfully produced with as few as 2 million reads, and common lung-related copy number alterations were readily detected. This is the first successful use of Nanopore sequencing for copy number profiling from plasma DNA. In this context, Nanopore represents a reliable alternative to Illumina sequencing, with the advantages of minute instrumentation costs and extremely short analysis time. The availability of protocols for Nanopore-based cell-free DNA analysis will make this analysis finally accessible, exploiting the full potential of liquid biopsy both for research and clinical purposes.

Lesson sul quarto stato della materia. Plasmi caldi e plasmi freddi. Produzione, confinamento e ricerca.

Properties and performance of materials are closely connected. In order to obtain piezoelectric and lasing optical quality, ZnO has to be free of defects and highly crystalline. Instead, conductivity depends upon such defects, making it not trivial to aim at a specific set of properties in a single step. In this regard, we studied in situ the effect of temperature as an additional knob to finely control such properties. In this contribution, plasma enhanced atomic layer deposited (PE-ALD) zinc oxide (ZnO) layers, deposited between 25 °C and 250 °C, were studied in situ during annealing in air, and the opto-chemical and structural characteristics of the oxides were followed as a function of temperature. In situ spectroscopic ellipsometry (SE) and X-ray diffraction (XRD) were adopted to identify temperature windows where major structural and optical changes in the material occurred. Two temperature regions were identified for the effusion of adsorbed gases and minor structural rearrangements (180-280 °C) and for the growth/coalescence of ZnO crystals and its densification (360-500 °C). The results were corroborated by ex situ SE, XRD, UV-Vis and X-ray photoelectron spectroscopy. The in situ study revealed differences among the ZnO layers deposited at different temperatures, giving additional insights on the material properties deposited by PE-ALD.

Predictability of burning plasmas is a key issue for designing and building credible future fusion devices. In this context, an important effort of physics understanding and guidance is being carried out in parallel to JET experimental campaigns in H and D by performing analyses and modelling towards an improvement of the understanding of DT physics for the optimization of the JET-DT neutron yield and fusion born alpha particle physics. Extrapolations to JET-DT from recent experiments using the maximum power available have been performed including some of the most sophisticated codes and a broad selection of models. There is a general agreement that 11-15 MW of fusion power can be expected in DT for the hybrid and baseline scenarios. On the other hand, in high beta, torque and fast ion fraction conditions, isotope effects could be favourable leading to higher fusion yield. It is shown that alpha particles related physics, such as TAE destabilization or fusion power electron heating, could be studied in ITER relevant JET-DT plasmas.

Runaway beam confinement and dissipation remain one of the main concern for ITER operation and a clear solution has not been found yet. ITER will be provided with a Shattered Pellet Injection (SPI) system as the primary disruption mitigation technique given the promising results provided by DIII-D [3]. To further study such technique an SPI system has been recently installed at JET and to provide reliable results an improved runaway beam position control system [2, 1] is proposed. We propose to use a dynamic observer to estimate in realtime the slow vertical drift of the runaway beam. This dynamic observer should replace the static one once the runaway beam is detected. The observer parameters have been optimized in order to fit the vertical position zp reconstructed using EFIT. The new observer has the same high frequency behavior of the standard one plus the capability of detecting the RE beam slow vertical drift. An innovative tool to improve the beam position control is also described. This method uses a graph data structure to store an adaptive probabilistic route-map that links different states of the plasma and that can be obtained either using experimental data or via simulators. Such structure is then used to provide an optimal control feedforward IP4 current references via reinforcement learning techniques.

In exploiting the analytical capabilities of plasma-based spectroscopy method, the evaluation of plasma parameters, particularly the plasma temperature, is a crucial step. In this work, a modified Saha-Boltzmann plot, which uses the columnar densities of atomic and ionic ground levels, is utilized to calculate the plasma temperature in a laser-induced plasma from an aluminum alloy target. The columnar densities are here calculated by quantifying the self-absorption of resonance lines. It is demonstrated that this is a promising method for accurate determination of plasma temperature. To validate the capability of this technique, plasma emission is measured at different gate delay times. For each delay, excitation temperature is calculated both by the conventional Saha-Boltzmann plot (by using the excited states) and by exploiting the new Columnar Density Saha-Boltzmann (CD-SB) plot. The results suggest that at later times of the plasma evolution, the CD-SB plot can be more suitable for the determination of plasma temperature than conventional Saha-Boltzmann plot. These findings provide a new approach for physical characterization of plasmas and give access to a wealth of information about the state of plasma. (C) 2019 The Authors. Published by Elsevier B.V. on behalf of Cairo University.

In this study, the effects of surface treatment of a low-temperature atmospheric oxygen plasma on basalt/epoxy composites were investigated to improve the hydrophobility of the composite surface. After the plasma treatment, the unmodified and surface treated composite laminates have been experimentally characterized by performing contact angle measurements, low-velocity impact tests and indentation depth on the impacted laminates. Results have showed a dependence of such composite properties on the plasma coating deposition and on the treatment parameters outlining the need to optimize both the plasma power and exposition time to plasma in order to assess the efficiency of the plasma treatment and establish the optimal processing conditions.

Collection of different research activities on detection measurements and modeling of meteoroid.

SiC detectors based on Schottky diodes with an interdigit or a thin continuous front electrode are employed for the characterization of plasma generated by low intensity (10 W/cm) laser were photons, electrons and keV ions are produced. The exposure to plasma induces the formation on the detector surface of debris and/or micrometric clusters of the target material whose concentration increases with the number of laser shots, leading to the formation of nanometric film after long exposure time. The presence of this deposit strongly modifies the electrical characteristics, the optical response and ion detection properties of the detectors. In particular, we monitored the current-voltage characteristics of SiC devices and we observed an increase of the leakage current, a decrease of the Schottky barrier height and a reduction of the photon detection efficiency in the UV region, by increasing the number of plasma shots. The modification in the electrical and optical properties have been observed after a high number of laser shots, and a simple cleaning procedure allows to remove the surface deposit and, in the case of the continuous front electrode device, to restore the initial electro-optical device performances. The differences related to geometry of the front electrode are discussed.

The main characteristics of the ENEA Discharge Produced Plasma (DPP) Extreme Ultraviolet (EUV) source are presented together with results of irradiations of various materials. The DPP EUV source, based on a Xe-plasma heated up to a temperature of 30 ÷ 40 eV, emits more than 30 mJ/sr/shot at 10 Hz rep. rate in the 10 ÷ 18 nm wavelength spectral range. The DPP is equipped with a debris mitigation system to protect particularly delicate components needed for patterning applications. The ENEA source has been successfully utilized for sub-micrometer pattern generation on photonic materials and on specifically designed chemically amplified resists. Details down to 100 nm have been replicated on such photoresists by our laboratory-scale apparatus for contact EUV lithography. Preliminary EUV irradiations of graphene films aimed at modifying its properties have been also performed.

Laser-induced breakdown (or plasma) spectroscopy (LIBS or LIPS) is a versatile analytical technique allowing the identification and quantification of atomic species composing a material through spectral analysis of the plasma generated by its irradiation with a high peak intensity (above ~108 W/cm2) laser pulse. For solid materials, it is a microdestructive technique involving the atomization and partial ionization of a typical amount of material between ~10 ng and ~1 µg/pulse. The technique can provide elemental profiles along depths of several hundred microns by using up to some thousand laser pulses (typical depth resolution between ~0.1 and ~1 µm/pulse). Several laboratory and portable LIBS devices are available on the market and many archaeometrical experimentations and concrete applications have been reported in the literature, which show the powerful performance of the technique. In this entry, LIBS basic principles and the state of the art of its application in the field of cultural heritage are presented.

Background: Gold nanorods (GNRs) display unique capacity to absorb and scatter near infrared light, which arises from their peculiar composition of surface plasmon resonances. For this reason, GNRs have become an innovative material of great hope in nanomedicine, in particular for imaging and therapy of cancer, as well as in photonic sensing of biological agents and toxic compounds for e.g. biomedical diagnostics, forensic analysis and environmental monitoring. As the use of GNRs is becoming more and more popular, in all these contexts, there is emerging a latent need for simple and versatile protocols for their modification with targeting units that may convey high specificity for any analyte of interest of an end-user.

Pinhole and CCD based quasi-optical x-ray imaging technique was applied to investigate the plasma of an electron cyclotron resonance ion source (ECRIS). Spectrally integrated and energy resolved images were taken from an axial perspective. The comparison of integrated images taken of argon plasma highlights the structural changes affected by some ECRIS setting parameters, like strength of the axial magnetic confinement, RF frequency and microwave power. Photon counting analysis gives precise intensity distribution of the x-ray emitted by the argon plasma and by the plasma chamber walls. This advanced technique points out that the spatial positions of the electron losses are strongly determined by the kinetic energy of the electrons themselves to be lost and also shows evidences how strongly the plasma distribution is affected by slight changes in the RF frequency.

Dust remobilization is one of the not yet fully understood mechanisms connected to the prompt erosion ofmaterial from plasma facing surfaces in fusion devices. As a part of a newly initiated cross-machine study,dust remobilization experiments have been performed on the COMPASS tokamak. Tungsten sampleswith well-defined deposited tungsten dust grains, prepared using a recently developed controlled pre-adhesion method, have been exposed to ELMy H-mode discharges as well as L-mode discharges withforced disruptions. Here we report on the technical aspects of the experiment realization as well as on theexperimental results of dust remobilization. The latter is discussed in the light of data from other machinesand a physical interpretation is suggested for the observed spatial localization of the dust remobilizationactivity. Evidence of rearrangement of isolated dust into clusters and strings is also presented.© 2017 Elsevier B.V. All rights reserved

Multiauthor Book om different approaches on plasma modeling